CVE-2026-55554: Dompdf chroot validation bypass in validateLocalUri

CVE-2026-55554 · Severity: medium · CVSS 4 · Published 2026-07-28

Dompdf is a PHP library used to convert HTML documents into PDF files. A security flaw in how the software restricts file access allows an attacker to bypass directory boundaries and view files they should not have access to. If an attacker can control the HTML content being converted, they could potentially read sensitive files located in sibling directories on the server, such as backup folders or administrative directories.

Technologies: Dompdf, dompdf/dompdf (Packagist). Vendors: Dompdf, Packagist.

Quick answers

Is CVE-2026-55554 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55554 being exploited in the wild.
How severe is CVE-2026-55554?
Medium severity, with a CVSS score of 4, published 28 July 2026.
Which products and versions are affected?
Dompdf < 3.1.6, <= 3.1.5; dompdf/dompdf (Packagist) < 3.1.6, ECOSYSTEM:introduced=0,fixed=3.1.6.
Is there a fix for CVE-2026-55554?
Yes. dompdf/dompdf (Packagist): upgrade to 3.1.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55554 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-55554?
Check whether you run Dompdf or dompdf/dompdf (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • dompdf/dompdf (Packagist): upgrade to 3.1.6 or later
    composer require dompdf/dompdf:^3.1.6

Technical details

A path traversal vulnerability exists in Dompdf's `validateLocalUri()` method due to improper validation of chroot boundaries. The library uses `realpath()` to normalize paths, which removes trailing directory separators. It then uses `strpos()` to verify if the requested file path starts with the allowed chroot path. Because the trailing slash is missing, a chroot defined as `/var/www` will incorrectly validate paths starting with `/var/www-admin` or `/var/www_backup`. An attacker who can provide HTML input to the converter can use this to include and read files from these sibling directories. The vulnerability is patched in version 3.1.6 by ensuring proper directory boundary enforcement.

Affected products

  • dompdf dompdf <= 3.1.5

Identifiers

  • CVE-2026-55554
  • GHSA-wvh6-f5jh-8gw4

Timeline

  • 2026-07-20: patched: Version 3.1.6 released
  • 2026-07-20: advisory: GitHub Security Advisory GHSA-wvh6-f5jh-8gw4 published
  • 2026-07-28: disclosed: CVE-2026-55554 published to NVD

References

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